Telephone system



March 21, 1944. J. LEVY ETAL TELEPHONE SYSTEM Filed Aug. 25, 1942 2 Sheets-sheaf 2- INVENTOR$ ATTORNEYS.

I L I r/uuus 55w; RAYMOND M MOO/E HEN/er .564 1/55,

Patented Mar. 21', 1944 TELEPHONE SYSTEM I I Julius Levy, Raymond M. Moore, and Henry Haves, LosAngeles, Cali1'..

Application August 25, 1942, sex-n1 No. 456,024 2 Claims. (cl. 179-84) This invention relates to improvements in telephone systems.

An object of the invention is to provide a telephone system wherein an audible signal may be impressed upon the circuit between two communicating parties or subscribers without interrupting the circuit which will be audible to the communicatingparties andwhich will indicate a that a third party or subscriber is endeavoring to be connected to one of the parties. i

In many instances two parties or subscribers may be engaging in a prolonged but unimportant conversation with each other at a time when a third party or subscriber is desirous 01' being connected to and conversing with one of these parties. However, under present telephone systems as now regulated, it is impossible for either of the engaged parties to be advised of the fact that a call has been made for one oi'them with the result that theirconversation which may be unimportant may be considerably prolonged in utter ignorance of the fact that a third party is endeavoring to put through a call which may be a very important message. By means of the present imfention if a party'puts'in a call for another party whose line is engaged the parties on the engaged circuit are advised of this fact by an audible signal. If theconversation between the engaged parties is important they mayat their option ignore the signal andc'ontinue withtheir conversation. On the other Fig. 2 is a wiring diagram of an automatic telephone system which employs dial type handsets, and in which the invention is embodied.

- Referring to the accompanying drawings wherein similar reference characters designate similar-parts throughout, and referring first to that embodiment of the invention illustrated in Fig. 1, 'the system illustrated is sho' as having merely three parties for purpo s of simplicity although it will be understood that the invention is equally applicable to any manually hand, if the conversation between the engaged parties is. relatively unimportant they may acquisce in the audible signal, hang .up their re- :ipective receivers, and this enable ing call to be put through.

Another object of the invention is to provide an automatic type of. telephone system with means for automatically advising two engaged parties that an incoming call of a third party'is being attempted, this being accomplished by an audible signal whichneed not be objectionable or interrupt the conversation and which may be the incomreadily ignored or acquiesced in by the busy parties. 7

With the foregoing and other objects in view, which will be mademanifest in the following detailed description and specifically pointed out in the appended claims, reference is had to theaccompanying drawings for an illustrative em-' bodiment of the invention, wherein:

Figure 1 is a wiring diagram ofone form of telephone that is manually controlled by a central operator; and

, shown,.to any of the jacks 22,23, or 24.

operated system whichusually has a multiplicity of parties.

In the system illustrated the parties stations are designated respectively at. A, B, and 0, there being hand-sets indicated at), II, and I2, re-

'spectively, equipped with cradle switches l3, l4,

and II, respectively, and callbells l6, l1, and I8, respectively. Each hand-set is shown as equipped 'with a battery is, 20, and 2|, respectively, and is connected to its respective jack 22, 23, and 24' on the operators switchboard. 25, 26, and 21 are indicating lamps associated with each station for indicating to the operator which party is calling in to the operator. On the operator's switchboard there are also parallel lacks 28,19,10, and II; any of which may be connected by 'patch'cords 32 only one of whicl i tis e operator's hand-set indicated at 0 may or may not be equipped with a cradle switch 33. This hand-set isnconnected to two contacts 34 and I engageable by a three-position switch" when" this switch is moved into its left-most position. In its neutral position, as illustrated, the switch it merely engages contacts 31 and 38 whichare connected through a switch 39 manuallyoperable by the operator to a buzzer {H0 or other'instrument capable of impressing on any'telephone circuit an audible signal. A choke coil 4| and a battery 42 may be connected across the buzzer and a condenser 43 of thenature of ;005 mi. is preferably connected in series with one, of the contacts, such as. the

contact 31. 1-Contacts N and "are en8 seable by the switch 38 when it is moved toward the rightsoas' to disengage not only contacts 34 and II, but also-contacts l1 and 38. Thesecontacts are connected through a condenser 46 which may be oi the natureof A mf. to a source of potential, not shown, that may be utilized to eflct a ringing of the call bells. The switch' plug 41 receivable in any I6 is connected to a of the jacks.

2 accuses c The operation oi the above-described con- 7 first be made, then a description of the applistructionis as follows: 11', for example, subscriber A desires to call subscriber B the liftin or the hand-set it from the cradle switch II hloses the circuit through'indicating lamp 2! indicating to the operator that subscriber 1A is rcalling in. The operator on ascertaining vfrom A As desire to call B, inserts plug 41 into jack 23 and throws the three-position switch ll to from Jack 23 and by means or patch cords 82 connects jacks :2 and a with jacks 2t and" which, it will be, observed, are connected in parallel with jacks' a and u. A and a can then proceed with their conversation. I

II during the time that, A and B are conversing ,Ccallsin,-theoperatorinsertsplugflinack. W

J 20 relay El to operate. The connector magnet 24 and may ascertain from C that C desires to call A. e operator may then insert plug 41 in one o the parallel jacks. such as 80 or ii, and with the switch ll in'the leit position engaging contacts 34 and ii as well as contacts 31 and ll, the operator can ascertain that the circuit between A and B is still busy and that conversation is going on. In order to advise A and B who may be conducting an unimportant con'-' versation that another party is desiring to call one 01' them and that C's message may be important, the operator then closes switch 39 while the switch 30 is either in its left position or in its neutral position engaging contacts 31 and II.-

On the closing of the switch "an audible signal created by the buzzer I is impressed on the line, that is the circuit connecting'parties A and B.

. This signal may be a low plain hum or the like which is not loud enough to be unpleasant or to necessarily interrupt the conversation going on between A and B. It A and B am conducting an important'conversation or do not wish to be interrupted they may ignore the signal impressed immediately put through by the operator to the party that C is calling, In this manner it is possible to audibly advise without-interruption busyiparties that a third party is desirous of calling. one of them so that it they so desire they may promptly terminate their conversation to receive the incoming call.

The invention may also be embodied in atelephone system of the automatic type, that is wherein dialing mechanisms are associated with the'h'and-set of each party to enable the making or a. call. We have illustrated the invention as having been incorporated in one such system although it will be understood that the invention is inno .way restricted thereto but'by'relatively' simple adaptation it may be incorporated in J other automatic systems of a similar character.

For purposes 01' illustrationw'e have shown on Fig. -2 the incorporation of the invention in a .wiringidiagram which; will be recognized by those skilled-inthe artaas being thatv ot the 82A21' P. A. 'x system; distributed by .the'

Automatic Electric company 01' Chicago, nuheie. For purposes of completeness and clarity a brief description 01' the operation 0! this system-wi l 7 cation or the invention thereto, and finally, a

, description of the operation and equipment embodying the invention will be made.

lifted a circuit is established through the telephone loop relay L-5, which is common to all line relays, and the upper or 1100 ohm winding or relay A-3. This causes relay A-8 to operate sufiiciently to close its make contacts indicated ,at II but not enough to operate its break-con- 'tacte indicated at El and 52. Relay A-3 thus operating partially, connects battery to the 1 control 0 bank contact on level A of the line finders associated with the callingline.

Relay H on closing completes a circuit through relay E-i in series with' the 30,0hm winding 0! the connector magnet A-i causing A4 does not operate when connected in series with the winding 01' relay E-i. Relay E-i on being energized closes a circuit to the ohm winding of the line finder magnet A-a-Z on, the

25 closing of its contact 53 and disconnects the finder start lead 54 from the succeeding finder connectors to prevent them from searching for. the marked" line. Magnet A-t closes a circuit by means of contacts 55 and 56 (contacts 58 having been closed by the energizing of the solenoid of relay E-l) to the upper 125 ohm winding I! of relay A--i causing A-.-i to operate. Magnet A-2 also prepares a pawl and ratchet mechanism, not shown-for advancing the line finder wipers one step which takes place every time that magnet A 2 is deenergized.

Relay A-l opens the circuit to the line finder magnet by disconnecting contacts es, Whenever the winding of magnet A2 is-deenergized by the breaking of contacts 68 its armature and pawli not shown, on restoring to, normal under the power of the restoring spring, step the wipers to the next set oi bank contacts and as magnet A-Z on deenergizing permits contacts 55 to open the I circuit through the upper (12% ohm winding 5? of relay A-i is opened. Whenever relay A-i is deener contacts as again close, thus re= establishing the circuit through contacts 53 that are held. closed by the relay e '12 ding E-i through v the magnet A-2. Thus there is an alternating performance or magnet A--2. and relay A-i,

A-2 closing the circuit through relay Ai, and

relay A-i opening the circuit through magnet A 2. Each time that et A--2 is scenerao counters a contact impressed with battery a circuit is then established throughthe lower 250-ohm winding of relay 5-3 which then opcrates in conjunction with the 1100 ohm. winding of relay A-3 to opemcontacts 5i and 52. A cir cult is also established through the upper 50 ohm winding is or relay 'D-i which on operating 1 through contacts II, closes the circuit through the lower ohm winding 6| of relay s-i. Peri;

tive battery from the same source (relay A-i) 7 is also connected to the control normal-lead CN terminating in the connectorba-nks to busy the calling line against intrusion.

When relay A,3 is thus operated completely" the breaking 01' contacts 5| disconnects its llllu ohm winding from' the battery side of the ascaoas line. The opening of contacts 52 disconnects relay L--! from the battery side of the line.

. permitting L! to release. This opens the circuit through relay E-l but as relay E-l is a slow-operating relay it remains operated for a very short interval following the release of relay.

L-i. Relay A-i is held operated through its lower winding M keeping the circuit to theiinder magnet A-2 open and thus stopping continuation of the stepping motion which is a function of the energizing of the magnet A2. The current through the upper .50 ohm winding of relay D-l causes'its armature to operate'suiih ciently to close the make contact 62 causing relay B--l to operate. When relay Bi operates it extends the f--" battery side of the calling line to the upper 125 ohm winding 51 of relay Al by the charge start equipment is completed through the charge start lead (chg. st.) when l battery is connected to the tone start lead the grounded contact disengaging contact 15.

closing contacts 63 and completes a circuit to the lower 200 ohm winding 84 of relay D-l causing relay D-I to operate completely. Relay D-l on operating disconnects its 50 ohm winding 59 and extends the battery side of the line to the lower winding 6! of relay A-l through the closing of contacts 60. Battery is now operated to the calling telephone loop through the windings and ii of relay A'|. Relay D-l also connects battery to the tone start lead (tone st.). by the closing of contacts to start the dial and busy tones and connects the dial tone through the twenty-fifth or last bank contact 61 oi connector level C and .005 mi. condenser 68 to the side of, the calling line to indicate that dialing 'may proceed. Relay E-I being a slowoperating relay and restoring shortly after relay D-l has operated, prepares a circuit'to the E-i relay of the two succeeding finder connectors so that other calls may be served by those finder connectors while the first finder connector is still occupied by the call under discussion.

When relay D-i is operated battery is connected to the tone' start lead (tone st.)- as above described. A circuit is completed t theupper 250 ohm Winding 89 of relay 8-5 which is in series with the 100 ohm winding III of relay R-i.

Relay S short circuits its upper 250 ohm wind- 1 ing 69 through contacts 1!, restores, removes the shunt, and again operates. This buzzer action of relay -S5 continues as long as battery is maintained on the tone start lead (tone st.). The current through the upper winding 69 of relay 8- fluctuates between maximum and zero each time S-S operates. and in this manner an alternating current is induced in the lower 250 ohm winding 12. This alternating current or tone is impressed upon the dial tone lead and is connected to the side of the calling line through a .005 mi. condenser by the closing of contact 80 of relay D-I.

When +1' battery is connected to the tone start lead the circuit of relay M-5 is also closed. Relay M-5 connects the tone generated by relay S-5 to the busy tone lead through contacts I3. It short circuits its own upper 500 ohm winding 14 by the closing of contacts I! and restores. The

restoring of relay M-B removes'the shunt from the upper 500 ohm winding 14 and relay M---5 again operatea- Relay M5 is a slow-operating relay being slow to operate and also-to release which causes the tone generated by relay 8-! and connected to the busy tone lead by contacts II to be periodically interrupted.

In the event. that storage battery charging equipment is soarranged that the charging is started each time a call is initiated thecircuit to However, relay B-l is of the slow release type and remains operated during the impulsing periods. When relay A--l releases momentarily a circuit is completed to the 30.0hm winding of connector magnet A4 it being understood that B-l remains operated to hold contacts I6 closed. A circuit from -the same battery source is also established to the lower 200 ohm winding 11 of rela'y C-i. This causes relay Cl to operate in multiple with the connector magnet A--4 on the first impulse-but since relay C--l is slowacting it remains operated during the rest of the impulses of the series.

Magnet A-4 in following the dialing impulses causes the wipers to be rotated step by step to the bank contacts corresmnding to the dialed digit. On the first step dial tone is disconnected. Relay Ci which operate on the first impulse short circuits the break contact of G-l in the p ing circuit so that this circuit will not open should G- -l operate While the wipers are being stepped over-busy line contacts.

'When the connector-wipers reach the bank contacts associated with the called line theficontrol'wiper C encounters battery, A circuit is thus completed to the winding of G-l causing this relay to operate. Relay G| opens at 18 part of an incomplete circuit tothe upper 100 7 ohm winding of relay H-i to prevent HI from called line.

operating in the event that the called line is later freed. It also connects busy tone through the .005 mi. condenser 68 to the side of the calling line. 1

Relay C-l' restores shortly after impulsing has ceased, opens the connector magnet circuit for connector magnet A-4 to prevent possible further stepping action and also switches the winding of G--i from the control wiper C to battery at a break contact of H-l to hold G-l operated until disconnection occurs. If the called line is idle relay C| restoring after impulsing has ceased closes a circuit through the ohm winding I! of' relay H-l, the control wiper C oi the connector, and the 250 ohm winding of a relay A-ithat is associated with the Current flowing through the 100 ohm winding 18 of relay H-l in series with the 250 ohm winding of relay A! is just sumcient to cause relay H-i to close its make'contacts 80. The battery potential connected to the control normal (CN) 0! the called line through the 100 ohm winding IQ of relay H--l busies the called line against intrusion by other calls; Relay H-l completes a circuit to its 500 ohm winding 8! and operates completely. Whenv fully operated this relay opens the circuits to relay C-l and magnet A-l so'that any subsequent operation of the dial at the calling teleing I! of relay I -l to the side oithe called line, connects the interrupted generator lead (int. gen.) to the side of the called line and connects battery to the generator start lead the circuit to winding .84, of relay Z-I, and

the momentum of the weighted reed 86 on restoring causes the circuit to the winding 81 of relay Z-J-to be closed momentarily. U-'-! is energized in series with'resistance 88 and operates with normal amplitude short circuits its winding, and closes the circ t to the winding 84 of relay Z--5. U-5 restores again, closes the circuit to the winding 81 oi 2-5 and continues to vibrate as long as. ground remains on'the generator start lead. The windings 84 and ll of relay' Z-|i are'in opposite directions and an alternating field is therefore generated which induces an alternating current of approximately 25 cycles per second in the upper windings 8| oi 2-5. If the system is arranged for automatic ringing, relay N5 also operates when 'battery is connected to the generator start lead and assuage current circuit from battery either direct or through some or the upper windings 88 of rel Z-l connected to the interrupted generator lead through the called telephone and the 100 ohm winding I2 of relay I -I to-"" battery. Relay F-l is operated sufllciently to close its make contacts designated at 82 irrespectiveof whether the .call station answers during hte ring or during a silent interval, This completes a circuit to the 400 ohm winding 03 of F-l. Relay F- i disconnects battery from the stone start lead; to stop generation or the dial and busy tones and disconnects battery from the generator start lead to stop generation or ringing current. Relay I -l also disconnects interrupted generator lead from the side or the called line, connects battery through the lower 125 ohm winding ll of relay Al to the side of the called line, disconnects the 100 ohm winding 82-0! F-l, irom the side or the called line. This transfer of thecalled line to relay A-l also extends the calling linethrough to the called line. Transmission battery isv now supplied to both ,telephones through the two windings s1 and oi oi relay A-i. The present invention embodies the additions to such a telephone system as will now be desets its weighted spring 89 into vibration. This intermittently closes the circuit to the 500 ohm winding of 'relay R-5, such winding being indicated .at 90. However, because of the slow to operate characteristics oi.R-.-l it does not operate until the weighted spring 01' N! has nearly come to rest. Relay R'I sets its own weighted scribed. Relay G-l is equipped withf a pair of contacts 94 which, when G-l is energized, close and feed busy signal from the busy tone lead to the side of the busy lines through-contacts of a signal relay 96. The busy signal derived from the busy tone lead is also fed through a; condenser 81 which is or proper capacity to give the desired tone volume to the busy lines. However, this busy tone is fed through contacts Ol 01' relay C-l which contacts are normally closed when relay 0-! is held open during the dialing I period. This keeps busy tone'ofl! oi the busy spring 8| into vibration thereby 'lntermitgently'f closing a-circuit to the winding of P--5.- Relay P! is also slow to operate and accordingly does not operate ,until the weighted spring of R-B has almost ceased vibrating. Relay P-B disconnects battery from the ringing lead or generator lead. (int. gen.) and connects thereto grounded ringing current. Relay P-'I also opens th circuit to N'-5 and connects a shunt around e 500 ohm winding ll oilN-I which causes N-S to be slow 'to restore. When N-i restores after the operation oi P-I it opens the circuit to R-t permitting 3-5 to restore. Relay R-J is slow to restore and on restoring; opens the circuit to P--l which likewise is slow to release.

I plying busy tone contacts as could be substituted.

Relay P-i removes the shuntfrom the 500 ohm winding 83 or N-I', connects .-+"-battery to winding 83 causing N-ll to reoperate and dislines that the selector maybe passing over in order to reach the called line. Relay G--l is also equipped with contacts so which puts positive battery on the signal relay. However, the signal relay is slow to open its contacts I! through 4.5 the use or a dashpot Ill or any equivalent device that may render it slow-opening. This is .sothat only a predetermined portion 01' busy tone ,will reach the busy parties so as not to be objectionable but will, nevertheless, be quite audible to them. It is not necessary that the tone be fed to the busy lines from the busy tone lead as a tone source but as busy tone is available on the busy tone lead it is connected in this manner for p sea of simplicity. Any other means for sup- By these additions it is possible for a third subscriber or a third party to call one of the two busy parties and on being advised by the back 'or the bus signal previo or N--! the foregoing sequence or operations of I relays N-I, R-5, and P-ll is repeated as long as battery is connected to the generator start lead. In this manner, the ringing current eii'ective to feed a slight signal to the calling and called parties. The calling and called parties conversationis not interrupted by the third par-.

tys incoming call. The third subscriber's inis Periodically interrupted to cause the bell at comingcall does not intrude nor is be able to the call telephone to ring intermittently. when.

P-t operates a circuit is completed groin battery superimposed byringing current through the called station ringer in series with soonparties likewise cannot hear the third subscriber. 7

However, as thecalling and called parties do denser and the 100 ohm winding 02 or I -l to hear'the signal that is impressed-on their circuit -i battery. A copper slug over one end oi the core oi relay F-l prevents F-l from operating from alternating current.

When the called station answers a loop is closed they are advised that some third party is desirous of communicating with one of them. If they a wish the calling and called parties may ignore the signal and continue with their conversation.

through that telephone, thus providing a direct On the other hand they may acquiescein the signal, restore their hand-sets, and thus restore the system to normal following which the third subscriber's call can be put through.

From the above described constructions it will be appreciated that by means of the present invention two parties to a telephone system who may be engaged in a prolonged but unimportant and possibly unnecessary conversation can be advised oi the desire of a third party to communicate with one of them. This desire may be com- -municated to them without interrupting their conversation and without any intrusion, and can be acquiesced in or ignored at the will of the busy parties.

While application of the invention to an automatic system has been illustrated and described in coniunction with the above-mentioned 32A21' P, A. X system, it will be readily appreciated 1 that with very little modification the invention or scope of the invention vas defined, bythe a'ppended claims.- 7 i I we claim:

1; In combination with a telephone system having means-for generating a-busy tone signal and applying it to the circuit of a third subscriber attempting to call a subscriber whose line is busy,

means for applyingta portion of the busy tone signal generated by said busy tonegenerating means to the circuit of the busy subscriber so 1 that the busy subscriber may be advised that his circuit is desired by the third subscribe 2. In combination with a telephone system having a busy tone generator, a relay for connecting the busy-tone generator to the circuit of a subscriber who calls another when that other's circuit is ens sed, and means for applying a portion of the signal from the busy tone generator to the busy circuit for a predetermined length of time only so that the busy subscriber vmay be advised thereby that he is being called.

JUHUBLIVY RAYMOND u'uooan nanny nsvns. 

